Group vi precursor compounds

ABSTRACT

The invention provides a facile process for preparing various Group VI precursor compounds useful in the vapor deposition of such Group VI metals onto solid substrates, especially microelectronic semiconductor device substrates. The process provides an effective means to obtain such volatile materials, which can then be sources of molybdenum, chromium, or tungsten-containing materials to be deposited on such substrates. Additionally, the invention provides a method for vapor deposition of such compounds onto microelectronic device substrates.

FIELD OF THE INVENTION

The present invention relates to certain precursors for the vapordeposition of certain Group VI-containing materials and to a method fortheir preparation.

BACKGROUND OF THE INVENTION

In consequence of its characteristics of extremely high melting point,low coefficient of thermal expansion, low resistivity, and high thermalconductivity, Group VI metals such as molybdenum, chromium, and tungstenare increasingly utilized in the manufacture of semiconductor devices,including use in diffusion barriers, electrodes, photomasks, powerelectronics substrates, low-resistivity gates, flat-panel displays, andinterconnects.

Such utility has motivated efforts to achieve deposition of molybdenum,chromium, and tungsten films for such applications that is characterizedby high conformality of the deposited film and high deposition rate toaccommodate efficient high-volume manufacturing operations. This in turnhas enabled efforts to develop improved molybdenum and tungsten sourcereagents useful in vapor deposition operations, as well as improvedprocess parameters utilizing such reagents.

SUMMARY OF THE INVENTION

The invention provides a facile process for preparing various Group VIprecursor compounds useful in the vapor deposition of certain Group VImetals onto solid substrates, especially microelectronic semiconductordevice substrates. The process provides an effective means to obtain andisolate such volatile solid or liquid materials, which can then besources of molybdenum, chromium, or tungsten-containing materials to bedeposited on such substrates. Additionally, the invention provides amethod for vapor deposition of such compounds onto microelectronicdevice substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a three-dimensional solid-state crystal structure depiction ofMoO₂Cl₂(CH₃CN)₂.

FIG. 2 is a three-dimensional solid-state crystal structure depiction ofWO₂Cl₂(CH₃CN)₂.

FIG. 3 is a plot of molybdenum deposition rate (Å/cycle) versus onsubstrate temperature (° C.) on a titanium nitride substrate usingMoO₂Cl₂(dimethoxyethane) as precursor.

FIG. 4 is a plot of XRF Carbon (X-ray fluorescence analysis for carbon)(μgm/cm²/100 Å Mo) versus substrate temperature (° C.) on a titaniumnitride substrate using MoO₂Cl₂(dimethoxyethane)₂ as precursor. FIGS. 3and 4 thus illustrate the process parameters under which Mo ispreferentially deposited versus MoC.

FIG. 5 is a three-dimensional solid-state crystal structure depiction ofMoO₂Cl₂(tetrahydrofuran)₂.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the invention provides a process for preparingcompounds of the Formula (I)

wherein M is chosen from molybdenum, chromium, and tungsten, X is chosenfrom fluoro, chloro, bromo, and iodo, and each L₁ and L₂ are the same ordifferent and constitute:

-   -   (i) a monodentate hydrocarbyl ligand coordinated with M, or    -   (ii) are taken together to form a bidentate hydrocarbyl ligand        coordinated with M; which comprises:        (A) contacting a compound of the formula

with (a) water containing about 0.1% (w/w) to about 48% (w/w) of acompound of the formula HX, and (b) a compound of the formula L₁ and/orL₂; followed by (B) isolation of the compound of Formula (I) as a solidor liquid.

As used herein, the term “hydrocarbyl” represents a C₂-C₁₆ groupcomprising carbon and hydrogen atoms and optionally containing at leastone nitrogen, sulfur, or oxygen atom. Such hydrocarbyl groups maycomprise straight- or branched-chain saturated, unsaturated, andpolyunsaturated alkylene and cycloalkylene groups and may besubstituted, for example, with one to five groups selected from C₁-C₆alkoxy, carboxyl, nitro, amino, C₂-C₆ aminocarbonyl, C₂-C₆ amido, cyano,C₂-C₇-alkoxycarbonyl, C₂-C₇-alkanoyloxy, hydroxy, aryl, heteroaryl,thiol, thioether, C₂-C₁₀ dialkylamino, C₃-C₁₅ trialkylammonium, andhalogen. The terms “C₁-C₆ alkoxy”, “C₂-C₇-alkoxycarbonyl”, and“C₂-C₇-alkanoyloxy” are used to denote groups corresponding to thestructures —OR³, —CO₂R³, and —OCOR³, respectively, wherein R³ is C₁-C₆alkyl or substituted C₁-C₆ alkyl. The terms “C₂-C₁₆ aminocarbonyl” and“C₂-C₁₆ amido” are used to denote groups corresponding to the structures—NHCOR⁴, —CONHR⁴, respectively, wherein R⁴ is C₁-C₇ alkyl. As notedabove, L₁ and L₂ comprise such hydrocarbyl groups, and contain at leastone nitrogen, sulfur, or oxygen atom.

L₁ and L₂ are chosen independently and represent monodentate ligands orare taken together to form bidentate ligands. In general, L₁ and L₂comprise a hydrocarbyl group having at least one oxygen, sulfur, ornitrogen atom. Such ligands may, for example, be chosen from t-butylnitrile, toluene, tetrahydrofuran, and acetonitrile, and such groupsoptionally substituted by one or more groups chosen from halo, cyano,nitro, C₁-C₆ alky, C₁-C₆alkoxy, tetrahydrofuran, C₁-C₆ alkoxycarbonyl,and phenyl. Further examples include 1,2-dimethoxyethane;1,2-diethoxyethane; 1,2-dimethoxypropane; N,N-dimethylacetamide;N,N-dimethylformamide; N,N-dimethylcyanoacetamide; diamines andtriamines such as N,N,N′,N′-tetramethylethylenediamine, ethylenediamine,hexaethylene diamine, diethylene triamine, and diethylenetriamine;dimethylsulfoxide; and glycols such as ethylene glycol, propyleneglycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, and 1,6-hexanediol.

The step (B) isolation of the compound of Formula (I) may be effected byextraction of the compound from the aqueous reaction mixture with awater-immiscible solvent, followed by evaporation of solvent orcrystallization. Alternately, a water-miscible solvent such as analcohol (e.g., ethanol) may be added to the aqueous solution to induceprecipitation of the desired compound of Formula (I). The solidcompounds of Formula (I) may be purified if desired, by crystallizationand/or vacuum sublimation.

It will be appreciated that the structure above depicting the compoundsof the invention is drawn in a two-dimensional format, not necessarilyrepresenting its three-dimensional orientation.

Additionally, the compounds of Formula (I) once formed, may be reactedwith additional/different compound(s) of formula L₁ and/or L₂ to form adifferent compound of Formula (I) via a displacement reaction.Accordingly, in a further embodiment, the invention provides the aboveprocess, further comprising the step of contacting the compound of theFormula (I) with a compound chosen from t-butyl nitrile, toluene,tetrahydrofuran, and acetonitrile, and such groups optionallysubstituted by one or more groups chosen from halo, cyano, nitro, C₁-C₆alky, C₁-C₆ alkoxy, tetrahydrofuran, C₁-C₆ alkoxycarbonyl, and phenyl;1,2-dimethoxyethane; 1,2-diethoxyethane; 1,2-dimethoxypropane;N,N-dimethylacetamide; N,N-dimethylformamide;N,N-dimethylcyanoacetamide; N,N,N′,N′-tetramethylethylenediamine,ethylenediamine, hexaethylene diamine, diethylene triamine, anddiethylenetriamine; dimethylsulfoxide; and ethylene glycol, propyleneglycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, and 1,6-hexanediol, to afford a compound of Formula (I)having a different ligand of formula L₁ and/or L₂.

In a further embodiment, the invention provides a compound of Formula(I)

wherein M is chosen from molybdenum, chromium, and tungsten, X is chosenfrom fluoro, chloro, bromo, and iodo, and each L₁ and L₂ are the same ordifferent and constitute:

-   -   (i) a monodentate hydrocarbyl ligand coordinated with M, or    -   (ii) are taken together to form a bidentate hydrocarbyl ligand        coordinated with M;        in solid or liquid form. In certain embodiments the compound of        Formula (I) possesses less than about 3 weight percent        impurities. In other embodiments, the compound of Formula (I)        possesses less than 1 weight percent impurities. In other        embodiments, the compound of Formula (I) is isolated in        crystalline form. Particular examples of such crystalline forms        of the compounds of Formula (I) include MoO₂Cl₂(CH₃CN)₂ and        WO₂Cl₂(CH₃CN)₂ and MoO₂Cl₂(tetrahydrofuran)₂. In a further        embodiment, the invention provides a compound having the formula        MoO₂Cl₂(CH₃CN)₂ in crystalline form and having the x-ray        crystallographic structure as shown in FIG. 1 . In a further        embodiment, the invention provides a compound having the formula        WO₂Cl₂(CH₃CN)₂ in crystalline form and having the x-ray        crystallographic structure as shown in FIG. 2 . In a further        embodiment, the invention provides a compound having the formula        MoO₂Cl₂(tetrahydrofuran)₂ in crystalline form and having the        x-ray crystallographic structure as shown in FIG. 5 . These        crystalline forms are further characterized in the Experimental        Section below.

In a further embodiment, the invention provides a compound having theformula MoO₂Cl₂(CH₃CN)₂, and having an orthorhombic crystal system, andunit cell dimensions of about

a = 12.0350(8) Å α = 90° b = 11.5956(9) Å β = 90° c = 26.5807(15) Å γ =90°.

In a further embodiment, the invention provides a compound having theformula WO₂Cl₂(CH₃CN)₂, and having an orthorhombic crystal system, andunit cell dimensions of about

a = 8.7091(6) Å α = 90° b = 8.2536(7) Å β = 90° c = 12.8021(8) Å γ =90°.

In a further embodiment, the invention provides a compound having theformula MoO₂Cl₂(tetrahydrofuran)₂, and having an orthorhombic crystalsystem, and unit cell dimensions of about

a = 7.4048(4) Å α = 90° b = 12.5437(6) Å β = 90° c = 13.7487(7) Å γ =90°.

As used herein the term “unit cell” refers to the smallest and simplestvolume element of a crystal that is completely representative of theunit of pattern of the crystal. The dimensions of the unit cell aredefined by six numbers: dimensions a, b, and c and angles α, β, and γ. Acrystal is an efficiently packed array of many unit cells.

As used herein, the term “orthorhombic unit cell” refers to a unit cellwherein a≠b≠c; α=β=γ=90°.

As used herein, “crystal lattice” refers to the array of points definedby the vertices of packed unit cells, as determined by single-crystalx-ray diffraction analysis.

As used herein, “space group” refers to the symmetry of a unit cell. Ina space group designation (e.g., C2) the capital letter indicates thelattice type and the other symbols represent symmetry operations thatcan be carried out on the unit cell without changing its appearance.

In the process of the invention, suitable water-immiscible solventsinclude dichloromethane, ethyl acetate, diethyl ether, toluene, benzene,pentane, and the like.

In one embodiment, the process is conducted at elevated temperatures,for example from about 20° C. to about 100° C.

The compounds of Formula (I) may also be prepared by utilizing astarting material of the formula

i.e., compounds of the general formula A₂MO₄, wherein M is chosen fromchromium, molybdenum, or tungsten, and A is chosen from group I and IImetal or ammonium cations. Examples of such cations include Li⁺, Na⁺,K⁺, NH₄ ⁺, alkylammonium compounds, and the like. Such compounds can besimilarly reacted with HX in the presence of a compound of the formulaL₁ and/or L₂ to afford the desired precursor compounds.

The process of the invention affords certain compounds which are in turnuseful in the vapor deposition of certain Group VI metals onto varioussubstrates, including microelectronic semiconductor device substrates.Thus, in another aspect, the invention provides a process for forming amaterial on a substrate, comprising contacting the substrate with acompound of the Formula (I)

wherein M is chosen from molybdenum, chromium, and tungsten, X is chosenfrom fluoro, chloro, bromo, and iodo, and each L₁ and L₂ are the same ordifferent and constitute:

-   -   (i) a monodentate hydrocarbyl ligand coordinated with M, or    -   (ii) are taken together to form a bidentate hydrocarbyl ligand        coordinated with M; depositing the molybdenum, chromium, or        tungsten-containing material onto the substrate, under vapor        deposition conditions.

The substrate utilized in the deposition process of the invention may beof any suitable type, and may for example comprise a semiconductordevice substrate, e.g., a silicon substrate, a silicon dioxidesubstrate, or other silicon-based substrate. In various embodiments, thesubstrate may comprise one or more metallic or dielectric substrates,for example, Co, Cu, Al, W, WN, WC, TiN, Mo, MoC, SiO₂, W, SiN, WCN,Al₂O₃, AlN, ZrO2, HfO₂, SiO₂, lanthanum oxide (La₂O₃), tantalum nitride(TaN), ruthenium oxide (RuO₂), iridium oxide (IrO₂), niobium oxide(Nb₂O₃), and yttrium oxide (Y₂O₃).

In certain embodiments, for example in the case of an oxide substratesuch as silicon dioxide, or alternatively a silicon or polysiliconsubstrate, the substrate may be processed or fabricated to include abarrier layer thereon, e.g., titanium nitride, for subsequentlydeposited material.

In one embodiment, the molybdenum, chromium, or tungsten-containinglayer deposited on the substrate surface may for example be formed bypulsed chemical vapor deposition (CVD) or atomic layer deposition (ALD)or other vapor deposition technique, without the prior formation of anucleation layer and thus directly with vapor derived from the compoundsof Formula (I). The respective Formula (I) vapor contacting steps may becarried out alternatingly and repetitively for as many cycles as aredesired to form the desired thickness of the molybdenum, chromium, ortungsten film. In various embodiments, the contact of the substrate(e.g., titanium nitride) layer with such vapor is conducted attemperature as low as 350°, and in other embodiments in a range of from3000° C. to 750° C.

With vapor derived from compounds of Formula (I), the molybdenum,chromium, or tungsten-containing material can be deposited directly ontothe substrate to form a bulk deposit of elemental molybdenum, chromium,or tungsten or their corresponding oxides. The concentration of H₂ iscritical towards the formation of metal or oxide, as greater than fourmolar equivalents or an excess of H₂ is required for metal formation.Less than four (4) molar equivalents of H₂ will result in the formationof varying amounts of an oxide of such metals, and thus will requirefurther exposure to H₂ in order to reduce the metal oxide thus formed.

In various embodiments, the molybdenum, chromium, or tungsten-containingmaterial is deposited on the substrate surface at temperature in a rangeof from 300° C. to 750° C. The process may be carried out so that thevapor deposition conditions produce deposition of elemental molybdenum,chromium, or tungsten as the metal-containing material on the substrate.The vapor deposition conditions may be of any suitable character, andmay for example comprise presence of hydrogen or other reducing gas, toform a bulk layer of elemental molybdenum, chromium, or tungsten on thesubstrate.

More generally, the broad method of forming a molybdenum, chromium, ortungsten-containing material on a substrate in accordance with thepresent disclosure may comprise vapor deposition conditions comprisingpresence of hydrogen or other reducing gas. The molybdenum, chromium, ortungsten-containing material may be deposited on the barrier layer orsurface in the presence or absence of hydrogen. For example, the barrierlayer may be constituted by titanium nitride, and the titanium nitridelayer may be contacted with vapor derived from the compounds of Formula(I) in the presence of hydrogen.

In another embodiment, an oxidizing co-reactant such as oxygen may beadded to the process when using compounds of Formula (I) as a means ofdepositing a metal oxide thin film, such as MoO₂, WO₃, and Cr₂O₃.

It will be appreciated that the method of the present invention may becarried out in numerous alternative ways, and under a wide variety ofprocess conditions. The process of the invention may for example becarried out in a process for making a semiconductor device on thesubstrate. The semiconductor device may be of any suitable type, and mayfor example comprise a DRAM device, 3-D NAND device, or other device ordevice integrated structure. In various embodiments, the substrate maycomprise a via in which the molybdenum-containing material is deposited.The device may, for example, have an aspect ratio of depth to lateraldimension that is in a range of from 10:1 to 40:1. In still otherembodiments, the device may be a film used in a flat-panel display ormobile device.

The process chemistry for depositing molybdenum-containing material inaccordance with the present invention may include deposition ofelemental molybdenum, Mo(0), by the reaction 2 MO₂Cl₂[(L₁)(L₂)]+6H₂→2M(wherein M=molybdenum, chromium, or tungsten)+4HCl+4H₂O. The molybdenum,chromium, or tungsten-containing material (M) deposited in accordancewith the method of the present invention may be characterized by anyappropriate evaluation metrics and parameters, such as deposition rateof the molybdenum, chromium, or tungsten-containing material, filmresistivity of the deposited molybdenum, chromium, ortungsten-containing material, film morphology of the depositedmolybdenum, chromium, or tungsten-containing material, film stress ofthe deposited molybdenum, chromium, or tungsten-containing material,step coverage of the material, and the process window or processenvelope of appropriate process conditions. Any appropriate evaluationmetrics and parameters may be employed, to characterize the depositedmaterial and correlate same to specific process conditions, to enablemass production of corresponding semiconductor products. Advantageously,the process of the invention is capable of depositing a film of highpurity molybdenum, chromium, or tungsten onto a semiconductor device.Accordingly, in a further aspect, the invention provides a semiconductordevice having a molybdenum film deposited thereon, wherein said filmcomprises greater than 99% molybdenum, chromium, or tungsten.

In certain embodiments, the disclosure relates to a method of forming amolybdenum, chromium, or tungsten-containing material on a substrate,comprising depositing molybdenum, chromium, or tungsten on the substratesurface by a chemical vapor deposition (CVD) process utilizing precursorcompounds of Formula (I), to produce the molybdenum, chromium, ortungsten-containing material on the substrate.

Such process may be carried out in any suitable manner as variouslydescribed herein. In specific embodiments, such method may be conductedwith a vapor deposition process comprising chemical vapor deposition,e.g., pulsed chemical vapor deposition. The method may be carried out sothat the resulting molybdenum, chromium, or tungsten-containing materialis composed essentially of elemental molybdenum, chromium, or tungsten,and in various embodiments the molybdenum, chromium, or tungsten may bedeposited on the substrate surface in the presence of hydrogen or othersuitable reducing gas. In other embodiments of the invention, theprecursors of Formula (I) and reducing gas may be pulsed sequentially todeposit the molybdenum film on pulsing with the pulse sequence beingoptimized for film conformality and film resistivity. The method may becarried out in the manufacture of a semiconductor device product, suchas a DRAM device, or a 3-D NAND, a logic device, a flat-panel display,or an IC packaging component.

Generally, the methods of the present disclosure for forming molybdenum,chromium, or tungsten-containing material on a substrate may be carriedout to achieve deposition of the molybdenum, chromium, ortungsten-containing material at high levels of step coverage, e.g., stepcoverage ranging from about 75% to about 100%.

This invention can be further illustrated by the following examples ofpreferred embodiments thereof, although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

EXPERIMENTAL SECTION

Using the following general procedure, the compounds of Formula (I) maybe prepared:

Synthetic Procedure No. 1.

MoO₃ (20.0 g, 138 mmol) was loaded into a 500 mL round bottom flaskequipped with a magnetic stir bar. HCl (200 mL, 37%) was added directlyto the MoO₃, the reaction flask outfitted with a water-cooled condenser(5° C.), and the resulting light-green suspension was heated to nearreflux (95° C.) using an oil bath. After ˜2 hours the reaction presentedas a clear light-green solution. The reaction was cooled to roomtemperature before being placed in an ice bath. At this point, DME (50mL) was added directly to the cooled solution and the reaction waswarmed to room temperature and stirred overnight. The following morningthe light-green solution was poured into a 1 L separation funnel andextracted with DCM (2×200 mL). The organic layers were combined, driedusing MgSO₄, filtered, placed in a 1 L round-bottom flask equipped witha magnetic stir bar, and the solvent removed under reduced pressure toyield MoO₂Cl₂(dimethoxyethane) as an off-white solid. Mass=12.68 g,Yield=31.8%. The product may be purified by vacuum sublimation (80° C. @25 mTorr). ¹H NMR (400 MHz, C₆D₆, 298K): δ 3.29 (s, 6H); 2.78 (s, 4H)ppm. ¹³C{1H} NMR (100 MHz, C₆D₆, 298K): δ 70.68, 64.13 ppm.

Synthetic Procedure No. 2

Of the general formula A₂MO₄, where M=chromium, molybdenum, or tungstenand A=lithium, sodium, or potassium.

Here, the general synthetic procedure and workup are very similar toprocedure No. 1.

i.e., compounds of the general formula A₂MO₄, wherein M is chosen fromchromium, molybdenum, or tungsten, and A is chosen group I and IImetals, or ammonium cations. Examples include Li⁺, Na⁺, K⁺, NH₄ ⁺,alkylammonium compounds, and the like.

Synthetic Procedure No. 3

Ligand substitution can be utilized to synthesize the compounds ofFormula (I). For example; the MoO₂Cl₂(N,N-dimethylformamide)₂ complexcan be made using Procedure No. 1 above, and then theN,N-dimethylformamide ligands substituted for dimethoxyethane viasolvolysis to generate MoO₂Cl₂(dimethoxyethane).

As noted above, FIG. 1 is a three-dimensional solid-state crystalstructure depiction of MoO₂Cl₂(CH₃CN)₂. This compound was subjected tox-ray crystallographic analysis and yielded the following data:

TABLE 1 Crystal data and structure refinement for MoO₂Cl₂(CH₃CN)₂.Identification code NB00618-002 Empirical formula C4 H6 Cl2 Mo N2 O2Formula weight 280.95 Temperature 100.0 K Wavelength 0.71073 Å Crystalsystem Orthorhombic Space group Pnma Unit cell dimensions a = 12.0350(8)Å α = 90°. b = 11.5956(9) Å β = 90°. c = 26.5807(15) Å γ = 90°. Volume3709.4(4) Å³ Z, Z′ 16, 4 Density (calculated) 2.012 Mg/m³ Absorptioncoefficient 1.945 mm⁻¹ F(000) 2176 Crystal size 0.24 × 0.19 × 0.18 mm³Theta range for data collection 1.857 to 26.718°. Index ranges −15 <= h<= 15, −14 <= k <= 14, −33 <= l <= 32 Reflections collected 22254Independent reflections 4134 [R(int) = 0.0475] Completeness to theta =25.242° 99.9% Absorption correction Semi-empirical from equivalents Max.and min. transmission 0.7454 and 0.6516 Refinement method Full-matrixleast-squares on F² Data/restraints/parameters 4134/0/222Goodness-of-fit on F² 1.008 Final R indices [I > 2sigma(I)] R1 = 0.0258,wR2 = 0.0518 R indices (all data) R1 = 0.0388, wR2 = 0.0558 Extinctioncoefficient 0.00013(2) Largest diff. peak and hole 0.492 and −0.462 e ·Å⁻³

TABLE 2 Atomic coordinates (×10⁴) and equivalent isotropic displacementparameters (Å² × 10³).. U(eq) is defined as one third of the trace ofthe orthogonalized U^(ij) tensor. x y z U(eq) Mo(4) 7248(1) 2500 4414(1)10(1) Mo(2) 2330(1) 7500 3151(1) 10(1) Mo(1) 2455(1) 2500 3069(1) 11(1)Mo(3) 7667(1) 7500 4464(1) 12(1) Cl(2) 4372(1) 2500 2868(1) 17(1) Cl(3)1038(1) 7500 2486(1) 19(1) Cl(4) 4104(1) 7500 3531(1) 15(1) Cl(5)5845(1) 7500 4786(1) 20(1) CI(7) 7535(1) 2500 3536(1) 17(1) Cl(8)7804(1) 2500 5264(1) 16(1) Cl(1)  877(1) 2500 3592(1) 19(1) Cl(6)9054(1) 7500 3833(1) 19(1) O(1) 2102(2) 3651(1) 2715(1) 19(1) N(2)3254(2) 6256(2) 2597(1) 13(1) N(1) 3109(2) 3737(2) 3706(1) 16(1) N(3)6849(2) 8742(2) 3887(1) 16(1) O(4) 6389(2) 1350(2) 4438(1) 18(1) O(3)8142(2) 6347(2) 4788(1) 21(1) C(2) 3871(2) 5026(2) 4428(1) 17(1) C(1)3436(2) 4302(2) 4022(1) 13(1) C(4) 4342(2) 4940(2) 1977(1) 18(1) C(7)9534(2) 4320(2) 4355(1) 10(1) N(4) 8773(2) 3745(2) 4367(1) 15(1) C(8)10517(2)  5057(2) 4342(1) 15(1) O(2) 1813(2) 8648(2) 3461(1) 19(1) C(3)3728(2) 5680(2) 2325(1) 13(1) C(6) 5822(2) 10073(2)  3259(1) 17(1) C(5)6407(2) 9324(2) 3608(1) 12(1)

TABLE 3 Bond lengths [Å] and angles [°] for MoO₂Cl₂(CH₃CN). Mo(4)—Cl(7)2.3601(9) Mo(4)—Cl(8) 2.3561(9) Mo(4)—O(4) 1.6885(17) Mo(4)—O(4)#11.6885(17) Mo(4)—N(4)#1 2.338(2) Mo(4)—N(4) 2.338(2) Mo(2)—Cl(3)2.3547(9) Mo(2)—Cl(4) 2.3623(9) Mo(2)—N(2) 2.343(2) Mo(2)—N(2)#22.343(2) Mo(2)—O(2) 1.6846(17) Mo(2)—O(2)#2 1.6846(17) Mo(1)—Cl(2)2.3672(10) Mo(1)—Cl(1) 2.3534(10) Mo(1)—O(1)#1 1.6867(17) Mo(1)—O(1)1.6867(17) Mo(1)—N(1) 2.355(2) Mo(1)—N(1)#1 2.355(2) Mo(3)—Cl(5)2.3528(10) Mo(3)—Cl(6) 2.3671(10) Mo(3)—N(3) 2.323(2) Mo(3)—N(3)#22.323(2) Mo(3)—O(3)#2 1.6885(17) Mo(3)—O(3) 1.6885(17) N(2)—C(3)1.137(3) N(1)—C(1) 1.135(3) N(3)—C(5) 1.134(3) C(2)—C(1) 1.462(3)C(4)—C(3) 1.462(3) C(7)—N(4) 1.133(3) C(7)—C(8) 1.461(3) C(6)—C(5)1.453(3) Cl(8)—Mo(4)—Cl(7) 155.09(4) O(4)#1—Mo(4)—Cl(7) 97.26(6)O(4)—Mo(4)—Cl(7) 97.26(6) O(4)#1—Mo(4)—Cl(8) 97.95(6) O(4)—Mo(4)—Cl(8)97.94(6) O(4)#1—Mo(4)—O(4) 104.33(13) O(4)#1—Mo(4)—N(4)#1 165.97(8)O(4)—Mo(4)—N(4) 165.97(8) O(4)—Mo(4)—N(4)#1 89.70(8) O(4)#1—Mo(4)—N(4)89.70(8) N(4)—Mo(4)—Cl(7) 80.39(5) N(4)#1—Mo(4)—Cl(7) 80.39(5)N(4)—Mo(4)—Cl(8) 80.08(5) N(4)#1—Mo(4)—Cl(8) 80.08(5) N(4)—Mo(4)—N(4)#176.27(11) Cl(3)—Mo(2)—Cl(4) 156.61(3) N(2)—Mo(2)—Cl(3) 80.86(5)N(2)#2—Mo(2)—Cl(3) 80.86(5) N(2)—Mo(2)—Cl(4) 80.76(5) N(2)#2—Mo(2)—Cl(4)80.76(5) N(2)#2—Mo(2)—N(2) 76.03(10) O(2)#2—Mo(2)—Cl(3) 97.08(6)O(2)—Mo(2)—Cl(3) 97.08(6) O(2)—Mo(2)—Cl(4) 97.18(7) O(2)#2—Mo(2)—Cl(4)97.18(7) O(2)#2—Mo(2)—N(2) 89.75(8) O(2)—Mo(2)—N(2)#2 89.75(8)O(2)—Mo(2)—N(2) 165.78(8) O(2)#2—Mo(2)—N(2)#2 165.78(8)O(2)#2—Mo(2)—O(2) 104.47(12) Cl(1)—Mo(1)—Cl(2) 156.82(4)Cl(1)—Mo(1)—N(1)#1 81.08(6) Cl(1)—Mo(1)—N(1) 81.08(6) O(1)—Mo(1)—Cl(2)96.88(6) O(1)#1—Mo(1)—Cl(2) 96.88(6) O(1)#1—Mo(1)—Cl(1) 97.24(6)O(1)—Mo(1)—Cl(1) 97.24(6) O(1)#1—Mo(1)—O(1) 104.56(12) O(1)—Mo(1)—N(1)#1165.24(8) O(1)#1—Mo(1)—N(1)#1 90.19(8) O(1)—Mo(1)—N(1) 90.20(8)O(1)#1—Mo(1)—N(1) 165.24(8) N(1)#1—Mo(1)—Cl(2) 80.59(6) N(1)—Mo(1)—Cl(2)80.59(6) N(1)#1—Mo(1)—N(1) 75.05(10) Cl(5)—Mo(3)—Cl(6) 156.17(4)N(3)#2—Mo(3)—Cl(5) 81.11(6) N(3)—Mo(3)—Cl(5) 81.11(6) N(3)—Mo(3)—Cl(6)80.24(6) N(3)#2—Mo(3)—Cl(6) 80.24(6) N(3)#2—Mo(3)—N(3) 76.59(10)O(3)#2—Mo(3)—Cl(5) 97.49(7) O(3)—Mo(3)—Cl(5) 97.49(7) O(3)—Mo(3)—Cl(6)97.00(7) O(3)#2—Mo(3)—Cl(6) 97.00(7) O(3)#2—Mo(3)—N(3) 89.38(8)O(3)—Mo(3)—N(3) 165.95(8) O(3)—Mo(3)—N(3)#2 89.38(8) O(3)#2—Mo(3)—N(3)#2165.95(8) O(3)#2—Mo(3)—O(3) 104.65(13) C(3)—N(2)—Mo(2) 177.7(2)C(1)—N(1)—Mo(1) 177.7(2) C(5)—N(3)—Mo(3) 177.0(2) N(1)—C(1)—C(2)179.3(3) N(4)—C(7)—C(8) 179.7(3) C(7)—N(4)—Mo(4) 177.4(2) N(2)—C(3)—C(4)179.7(3) N(3)—C(5)—C(6) 178.8(3) Symmetry transformations used togenerate equivalent atoms: #1 x, −y + 1/2, z #2 x, −y + 3/2, z

TABLE 4 Anisotropic displacement parameters (Å² × 10³) forMoO₂Cl₂(CH₃CN). The anisotropic displacement factor exponent takes theform: −2π²[h² a*²U¹¹ + . . . + 2 h k a* b* U¹²] U¹¹ U²² U³³ U²³ U¹³ U¹²Mo(4)  9(1)  9(1) 13(1) 0   2(1) 0 Mo(2)  9(1) 10(1) 10(1) 0   3(1) 0Mo(1) 13(1) 10(1) 10(1) 0 −3(1) 0 Mo(3) 15(1) 9(1) 11(1) 0 −4(1) 0 Cl(2)16(1) 18(1) 17(1) 0   3(1) 0 Cl(3) 12(1) 23(1) 22(1) 0 −4(1) 0 Cl(4)13(1) 18(1) 13(1) 0 −1(1) 0 Cl(5) 20(1) 19(1) 21(1) 0   3(1) 0 Cl(7)19(1) 20(1) 13(1) 0   0(1) 0 Cl(8) 19(1) 17(1) 13(1) 0   2(1) 0 Cl(1)15(1) 20(1) 23(1) 0   4(1) 0 Cl(6) 17(1) 20(1) 21(1) 0   2(1) 0 O(1)21(1) 16(1) 21(1)   5(1) −4(1)   1(1) N(2) 11(1) 12(1) 17(1)   1(1)−1(1)   2(1) N(1) 18(1) 14(1) 17(1) −2(1)   0(1) −1(1) N(3) 18(1) 13(1)17(1) −2(1) −1(1)   1(1) O(4) 17(1) 15(1) 21(1) −1(1)   3(1) −5(1) O(3)25(1) 16(1) 22(1)   4(1) −2(1)   4(1) C(2) 20(2) 16(2) 17(2) −5(1)  0(1)   1(1) C(1) 11(1) 13(1) 15(1)   5(1)   4(1)   4(1) C(4) 21(2)16(2) 16(1) −2(1)   4(1)   2(1) C(7) 16(1)  9(1) 6(1)   1(1)   1(1)  3(1) N(4) 17(1) 14(1) 13(1) −1(1)   0(1)   2(1) C(8) 14(2) 16(2) 15(1)  3(1) −3(1) −4(1) O(2) 17(1) 21(1) 20(1) −4(1)   5(1)   3(1) C(3) 12(1)13(1) 13(1)   3(1) −4(1) −2(1) C(6) 18(2) 15(2) 18(1)   7(1) −3(1) −1(1)C(5) 13(1) 10(1) 14(1) −2(1)   2(1) −2(1)

TABLE 5 Hydrogen coordinates (×10⁴) and isotropic displacementparameters (Å² × 10³) for MoO₂Cl₂(CH₃CN). x y z U(eq) H(2A) 3835 58374327 26 H(2B) 4645 4814 4496 26 H(2C) 3425 4910 4732 26 H(4A) 3937 48841658 27 H(4B) 4422 4169 2124 27 H(4C) 5080 5270 1916 27 H(8A) 10874 49954012 22 H(8B) 11040 4812 4604 22 H(8C) 10298 5860 4402 22 H(6A) 625610150 2949 26 H(6B) 5722 10835 3412 26 H(6C) 5094 9740 3181 26

As noted above, FIG. 2 is a three-dimensional solid-state crystalstructure depiction of WO₂Cl₂(CH₃CN)₂.

TABLE 6 Crystal data and structure refinement for WO₂Cl₂(CH₃CN)₂.Identification code NB00666-001 Empirical formula C4 H6 Cl2 N2 O2 WFormula weight 368.86 Temperature 100.0 K Wavelength 0.71073 Å Crystalsystem Orthorhombic Space group Pbcn Unit cell dimensions a = 8.7091(6)Å α = 90°. b = 8.2536(7) Å β = 90°. c = 12.8021(8) Å γ = 90°. Volume920.23(12) Å³ Z 4 Density (calculated) 2.662 Mg/m³ Absorptioncoefficient 13.088 mm⁻¹ F(000) 672 Crystal size 0.37 × 0.35 × 0.33 mm³Theta range for data collection 3.183 to 28.277°. Index ranges −11 <= h<= 10, −11 <= k <= 6, −16 <= l <= 16 Reflections collected 5168Independent reflections 1139 [R(int) = 0.0281] Completeness to theta =25.242° 99.9% Absorption correction Semi-empirical from equivalents Max.and min. transmission 0.6035 and 0.3693 Refinement method Full-matrixleast-squares on F² Data/restraints/parameters 1139/0/52 Goodness-of-fiton F² 1.133 Final R indices [I > 2sigma(I)] R1 = 0.0183, wR2 = 0.0431 Rindices (all data) R1 = 0.0256, wR2 = 0.0459 Extinction coefficient n/aLargest diff. peak and hole 0.641 and −1.611 e · Å⁻³

TABLE 7 Atomic coordinates (×10⁴) and equivalent isotropic displacementparameters (Å² × 10³) for WO₂Cl₂(CH₃CN)₂. U(eq) is defined as one thirdof the trace of the orthogonalized U^(ij) tensor. x y z U(eq) W(1) 50003420(1) 2500  7(1) Cl(1) 7382(1) 4003(1) 3276(1) 14(1) O(1) 5680(3)2149(3) 1552(2) 12(1) N(1) 4324(4) 5646(4) 3495(2) 12(1) C(2) 3798(5)8375(4) 4431(3) 14(1) C(1) 4080(4) 6841(4) 3911(3) 11(1)

TABLE 8 Bond lengths [Å] and angles [°] for WO₂Cl₂(CH₃CN)₂. W(1)—Cl(1)#12.3502(9) W(1)—Cl(1) 2.3502(9) W(1)—O(1)#1 1.710(3) W(1)—O(1) 1.710(3)W(1)—N(1)#1 2.312(3) W(1)—N(1) 2.312(3) N(1)—C(1) 1.141(5) C(2)—H(2A)0.9800 C(2)—H(2B) 0.9800 C(2)—H(2C) 0.9800 C(2)—C(1) 1.452(5)Cl(1)—W(1)—Cl(1)#1 156.36(4) O(1)—W(1)—Cl(1) 96.89(9) O(1)#1—W(1)—Cl(1)97.55(9) O(1)—W(1)—Cl(1)#1 97.55(9) O(1)#1—W(1)—Cl(1)#1 96.89(9)O(1)—W(1)—O(1)#1 104.30(17) O(1)—W(1)—N(1) 165.20(12) O(1)—W(1)—N(1)#190.48(11) O(1)#1—W(1)—N(1) 90.48(11) O(1)#1—W(1)—N(1)#1 165.20(12)N(1)—W(1)—Cl(1)#1 81.11(8) N(1)#1—W(1)—Cl(1)#1 80.15(8)N(1)#1—W(1)—Cl(1) 81.11(8) N(1)—W(1)—Cl(1) 80.15(8) N(1)—W(1)—N(1)#174.75(15) C(1)—N(1)—W(1) 172.6(3) H(2A)—C(2)—H(2B) 109.5H(2A)—C(2)—H(2C) 109.5 H(2B)—C(2)—H(2C) 109.5 C(1)—C(2)—H(2A) 109.5C(1)—C(2)—H(2B) 109.5 C(1)—C(2)—H(2C) 109.5 N(1)—C(1)—C(2) 178.8(4)Symmetry transformations used to generate equivalent atoms: #1 −x + 1,y, −z + 1/2

TABLE 9 Anisotropic displacement parameters (Å² × 10³) forWO₂Cl₂(CH₃CN)₂. The anisotropic displacement factor exponent takes theform: −2π²[h² a*²U¹¹ + . . . + 2 h k a* b* U¹²] U¹¹ U²² U³³ U²³ U¹³ U¹²W(1)  8(1)  5(1)  7(1) 0 −1(1) 0 Cl(1) 11(1) 14(1) 16(1) −1(1) −4(1)−1(1) O(1) 12(1) 11(1) 14(1) −1(1) −2(1)   1(1) N(1) 10(2) 12(2) 12(2)  0(1)   0(1) −1(1) C(2) 21(2)  8(2) 12(2) −3(1) −3(2)   2(1) C(1) 11(2)11(2) 11(2)   1(1) −4(2) −2(1)

TABLE 10 Hydrogen coordinates (×10⁴) and isotropic displacementparameters (Å² × 10³) for WO₂Cl₂(CH₃CN)₂. x y z U(eq) H(2A) 3864 92583921 16 H(2B) 4569 8540 4979 16 H(2C) 2772 8363 4744 16

As noted above, FIG. 5 is a three-dimensional solid-state crystalstructure depiction of MoO₂Cl₂(THF)₂. (THF=tetrahydrofuran) Thiscompound was subjected to x-ray crystallographic analysis and yieldedthe following data:

TABLE 11 Crystal data and structure refinement for MoO₂Cl₂(THF)₂.Empirical formula C8 H16 Cl2 Mo O4 Molecular formula C8 H16 Cl2 Mo O4Formula weight 343.05 Temperature 200 K Wavelength 0.71073 Å Crystalsystem Orthorhombic Space group P2₁2₁2₁ Unit cell dimensions a =7.4048(4) Å □ = 90°. b = 12.5437(6) Å □ = 90°. c = 13.7487(7) Å □ = 90°.Volume 1277.03(11) Å³ Z 4 Density (calculated) 1.784 Mg/m³ Absorptioncoefficient 1.437 mm⁻¹ F(000) 688 Crystal size 0.15 × 0.15 × 0.1 mm³Crystal color, habit clear colourless block Theta range for datacollection 2.198 to 26.382°. Index ranges −9 <= h <= 9, −15 <= k <= 13,−17 <= l <= 17 Reflections collected 11549 Independent reflections 2611[R(int) = 0.0731] Completeness to theta = 25.242° 99.9% Absorptioncorrection Semi-empirical from equivalents Max. and min. transmission0.4652 and 0.3891 Refinement method Full-matrix least-squares on F²Data/restraints/parameters 2611/0/136 Goodness-of-fit on F² 1.065 FinalR indices [I > 2sigma(I)] R1 = 0.0332, wR2 = 0.0838 R indices (all data)R1 = 0.0361, wR2 = 0.0858 Absolute structure parameter 0.00(5)Extinction coefficient n/a Largest diff. peak and hole 0.360 and −0.510e · Å⁻³

TABLE 12 Atomic coordinates (×10⁴) and equivalent isotropic displacementparameters (Å² × 10³) For Example 11, U(eq) is defined as one third ofthe trace of the orthogonalized U^(ij) tensor. x y z U(eq) Mo(1) 5728(1)5036(1) 4146(1) 36(1) Cl(2) 6796(2) 6222(1) 2947(1) 42(1) Cl(1) 5665(2)3642(1) 5296(1) 59(1) O(3) 7484(4) 3874(3) 3290(2) 33(1) O(4) 8555(5)5286(3) 4799(3) 37(1) O(2) 3868(5) 4641(4) 3542(4) 60(1) O(1) 4986(7)6018(4) 4890(3) 63(1) C(6) 10956(8)  5056(5) 5895(4) 56(2) C(1) 7073(9)2746(4) 3220(4) 44(1) C(8) 9173(9) 6336(5) 5068(4) 54(2) C(2)  8331(10)2315(4) 2433(4) 52(2) C(4) 9009(8) 4133(5) 2657(4) 45(1) C(7) 10698(10)6210(6) 5705(8) 97(3) C(3) 9888(9) 3099(5) 2452(5) 53(2) C(5)  9912(11)4520(5) 5131(5) 64(2)

TABLE 13 Bond lengths [Å] and angles [°] for MoO₂Cl₂(THF)₂. Mo(1)—Cl(2)2.3575(14) Mo(1)—Cl(1) 2.3576(15) Mo(1)—O(3) 2.280(3) Mo(1)—O(4)2.300(4) Mo(1)—O(2) 1.683(4) Mo(1)—O(1) 1.692(4) O(3)—C(1) 1.451(6)O(3)—C(4) 1.462(6) O(4)—C(8) 1.442(6) O(4)—C(5) 1.463(8) C(6)—H(6A)0.9900 C(6)—H(6B) 0.9900 C(6)—C(7) 1.483(9) C(6)—C(5) 1.469(8)C(1)—H(1A) 0.9900 C(1)—H(1B) 0.9900 C(1)—C(2) 1.526(8) C(8)—H(8A) 0.9900C(8)—H(8B) 0.9900 C(8)—C(7) 1.438(9) C(2)—H(2A) 0.9900 C(2)—H(2B) 0.9900C(2)—C(3) 1.516(9) C(4)—H(4A) 0.9900 C(4)—H(4B) 0.9900 C(4)—C(3)1.478(8) C(7)—H(7A) 0.9900 C(7)—H(7B) 0.9900 C(3)—H(3A) 0.9900C(3)—H(3B) 0.9900 C(5)—H(5A) 0.9900 C(5)—H(5B) 0.9900 Cl(1)—Mo(1)—Cl(2)160.67(6) O(3)—Mo(1)—Cl(2) 81.43(9) O(3)—Mo(1)—Cl(1) 83.31(10)O(3)—Mo(1)—O(4) 76.68(12) O(4)—Mo(1)—Cl(2) 83.21(10) O(4)—Mo(1)—Cl(1)81.78(10) O(2)—Mo(1)—Cl(2) 96.61(17) O(2)—Mo(1)—Cl(1) 95.55(17)O(2)—Mo(1)—O(3) 91.38(18) O(2)—Mo(1)—O(4) 167.97(18) O(2)—Mo(1)—O(1)104.3(2) O(1)—Mo(1)—Cl(2) 94.13(16) O(1)—Mo(1)—Cl(1) 97.36(16)O(1)—Mo(1)—O(3) 164.1(2) O(1)—Mo(1)—O(4) 87.7(2) C(1)—O(3)—Mo(1)122.6(3) C(1)—O(3)—C(4) 109.8(4) C(4)—O(3)—Mo(1) 127.3(3)C(8)—O(4)—Mo(1) 120.9(3) C(8)—O(4)—C(5) 107.6(5) C(5)—O(4)—Mo(1)131.1(4) H(6A)—C(6)—H(6B) 108.9 C(7)—C(6)—H(6A) 110.8 C(7)—C(6)—H(6B)110.8 C(5)—C(6)—H(6A) 110.8 C(5)—C(6)—H(6B) 110.8 C(5)—C(6)—C(7)104.7(5) O(3)—C(1)—H(1A) 110.7 O(3)—C(1)—H(1B) 110.7 O(3)—C(1)—C(2)105.4(5) H(1A)—C(1)—H(1B) 108.8 C(2)—C(1)—H(1A) 110.7 C(2)—C(1)—H(1B)110.7 O(4)—C(8)—H(8A) 110.2 O(4)—C(8)—H(8B) 110.2 H(8A)—C(8)—H(8B) 108.5C(7)—C(8)—O(4) 107.8(5) C(7)—C(8)—H(8A) 110.2 C(7)—C(8)—H(8B) 110.2C(1)—C(2)—H(2A) 111.2 C(1)—C(2)—H(2B) 111.2 H(2A)—C(2)—H(2B) 109.1C(3)—C(2)—C(1) 102.9(5) C(3)—C(2)—H(2A) 111.2 C(3)—C(2)—H(2B) 111.2O(3)—C(4)—H(4A) 110.7 O(3)—C(4)—H(4B) 110.7 O(3)—C(4)—C(3) 105.0(4)H(4A)—C(4)—H(4B) 108.8 C(3)—C(4)—H(4A) 110.7 C(3)—C(4)—H(4B) 110.7C(6)—C(7)—H(7A) 110.0 C(6)—C(7)—H(7B) 110.0 C(8)—C(7)—C(6) 108.4(6)C(8)—C(7)—H(7A) 110.0 C(8)—C(7)—H(7B) 110.0 H(7A)—C(7)—H(7B) 108.4C(2)—C(3)—H(3A) 111.0 C(2)—C(3)—H(3B) 111.0 C(4)—C(3)—C(2) 103.7(5)C(4)—C(3)—H(3A) 111.0 C(4)—C(3)—H(3B) 111.0 H(3A)—C(3)—H(3B) 109.0O(4)—C(5)—C(6) 106.4(5) O(4)—C(5)—H(5A) 110.4 O(4)—C(5)—H(5B) 110.4C(6)—C(5)—H(5A) 110.4 C(6)—C(5)—H(5B) 110.4 H(5A)—C(5)—H(5B) 108.6Symmetry transformations used to generate equivalent atoms:

TABLE 14 Anisotropic displacement parameters (Å² × 10³) forMoO₂Cl₂(THF)₂. The anisotropic displacement factor exponent takes theform: −2□²[h² a*²U¹¹ + . . . + 2 h k a* b* U¹²] U¹¹ U²² U³³ U²³ U¹³ U¹²Mo(1) 30(1) 33(1) 44(1) −1(1)  12(1)   0(1) Cl(2) 47(1) 32(1) 46(1)  7(1) −1(1)   0(1) Cl(1) 77(1) 48(1) 52(1)  10(1)  30(1) −8(1) O(3)35(2) 24(2) 38(2) −4(1)  9(2) −2(1) O(4) 43(2) 25(2) 42(2) −5(2) −5(2)  0(2) O(2) 31(2) 63(3) 87(3)   5(3)   1(2) −6(2) O(1) 65(3) 52(3) 72(3)−10(2)    32(3)  12(2) C(6) 43(3) 66(5) 59(4)   2(4)   4(2) −6(3) C(1)53(3) 28(3) 50(3) −8(2) −2(3) −7(3) C(8) 75(4) 31(3) 56(4) −6(3)−11(3)   −12(3)   C(2) 80(4) 33(3) 42(3) −8(3) −7(3)  16(3) C(4) 49(3)39(3) 46(3) −3(3)  19(3)   0(3) C(7) 73(5) 45(4) 172(9)  −34(5)  −58(6)    10(4) C(3) 58(3) 42(4) 59(4) −1(3)  20(3)  10(3) C(5) 70(4)43(4) 78(5) −5(3) −24(4)    13(3)

TABLE 15 Hydrogen coordinates (×10⁴) and isotropic displacementparameters (Å² × 10³) for MoO₂Cl₂(THF)₂. x y z U(eq) H(6A) 12249 48625854 67 H(6B) 10496 4862 6548 67 H(1A) 5794 2636 3035 52 H(1B) 7299 23853848 52 H(8A) 9528 6741 4481 64 H(8B) 8197 6730 5404 64 H(2A) 8745 15842591 62 H(2B) 7731 2309 1790 62 H(4A) 9857 4623 2988 54 H(4B) 8586 44712048 54 H(7A) 10480 6593 6324 116 H(7B) 11794 6512 5398 116 H(3A) 107662913 2968 64 H(3B) 10521 3115 1817 64 H(5A) 10710 4310 4586 76 H(5B)9322 3872 5392 76

The table below illustrates the various physical properties for certaincompounds of Formula (I):

STA-DSC Residual Example Compound M.P. T₅₀ (° C.) Mass (%) NumberMoO₂Cl₂(DME) 128.4 184.4 1.69 1 MoO₂Cl₂(DMM) 200.4 46.36 2MoO₂Cl₂(1,2-DMP) 131.8 185.0 40.89 3 MoO₂Cl₂(DMA)₂ 124.7 238.3 17.06 4MoO₂Cl₂(DMF)₂ 162.6 232.0 9.93 5 MoO₂Cl₂(MeCN)₂ 112.4 143.5 2.61 6MoO₂Cl₂(tBuCN)_(x) 95.3 135.7 4.55 7 MoO₂Cl₂(iPrCN)_(x) 69.9 134.1 3.158 MoO₂Cl₂(DMCA) n/a 64.45 9 MoO₂Cl₂(TMEN) n/a 57.12 10 MoO₂Cl₂(THF)₂138.1 18.77 11

Abbreviations

DME = 1,2-dimethoxyethane DMM = 1,2-dimethoxymethane 1,2-DMP =1,2-dimethoxypropane DMA = N,N-dimethylacetamide DMF =N,N-dimethylformamide DMCA = N,N-dimethylcyanoacetamide TMEN =N,N,N′,N′-tetramethylethylenediamine CN = nitrile THF = tetrahydrofuran

STA-DSC:

simultaneous thermal analysis—differential scanning calorimetry

What is claimed is: 1-20. (canceled)
 21. A compound of the Formula (I)

wherein M is chosen from molybdenum, tungsten, and chromium, X is chosenfrom fluoro, chloro, bromo, and iodo, and each L₁ and L₂ are the same ordifferent and constitute: (i) a monodentate hydrocarbyl ligandcoordinated with M, or (ii) are taken together to form a bidentatehydrocarbyl ligand coordinated with M.
 22. The compound of claim 21,wherein X is fluoro.
 23. The compound of claim 21, wherein X is chloro.24. The compound of claim 21, wherein X is bromo.
 25. The compound ofclaim 21, wherein X is iodo.
 26. The compound of claim 21, wherein thecompound is MoO₂Cl₂(CH₃CN)₂.
 27. The compound of claim 26, wherein thecompound has a unit cell of about: a = 12.0350(8) Å α = 90° b =11.5956(9) Å β = 90° c = 26.5807(15) Å γ = 90°.


28. The compound of claim 21, wherein the compound is WO₂Cl₂(CH₃CN)₂.29. The compound of claim 28, wherein the compound has a unit cell ofabout: a = 8.7091(6) Å α = 90° b = 8.2536(7) Å β = 90° c = 12.8021(8) Åγ = 90°.


30. The compound of claim 21, wherein the compound isMoO₂Cl₂(tetrahydrofuran)₂.
 31. The compound of claim 30, wherein thecompound has a unit cell of about: a = 7.4048(4) Å α = 90° b =12.5437(6) Å β = 90° c = 13.7487(7) Å γ = 90°.